Sweet Sixteen
by damnitjillkatherine
Summary: Sam hits puberty and develops a massive crush on Dean. Wincest, underage.


**Sweet Sixteen  
><strong>Disclaimer: Not mine. If only...  
>Rating: NC-17. Wincest, underage<br>Summary: Sam hits puberty and develops a massive crush on Dean.

* * *

><p>Sam was thirteen when he started noticing the changes. Sure, he'd read books and seen movies in health class about puberty, but it was one of those things he never thought would actually happen to him. Figured he'd get eaten by something before that.<p>

Hair started popping up in strange places. He realized he needed to borrow his brother's deodorant. Dean teased him mercilessly every time his voice cracked and broke. And then there was the morning wood.

Sam wasn't completely naïve. You don't spend your entire life living in close quarters with Dean Winchester without learning a thing or two about sex and how the male body works. But Sam was still not prepared to wake up one morning with an ache in his groin and a tent in his shorts. Luckily, he was the first one up, and he was able to dash to the bathroom without being seen.

Sam locked the door and stared down at his problem, unsure as to how he was supposed to proceed. He'd walked in on Dean jerking off once or twice, so he knew the basic mechanics, but he was still embarrassed. Figuring he'd better just get to it before his brother woke up and started pounding down the door, he closed his eyes, pushed his shorts down, and took hold of himself.

Immediately, his hips bucked, his eyes flew open, and a gasp escaped his lips. The gasp became a moan that he quickly covered with his free hand as his hips moved of their own accord. Apparently, his body knew exactly how this was supposed to work. _No wonder Dean does this so often! _Sam thought, biting into the palm of his hand. That thought automatically called up an image of the time he'd walked in on his brother right at the moment of his release, head thrown back, lips parted, thick white fluid pumping over his fist. Sam gasped as his own climax took him by surprise, spurting all over the sink and onto the mirror. He started at his reflection, post-orgasm bliss tempered by vague horror.

This could not be good.

...

By the time Sam turned fourteen, he had "accidentally" caught Dean jerking off six more times: three times in the shower, twice in the motel rooms, and one very memorable time in the backseat of the Impala while Dad drove and Sam pretended to be asleep. He'd never been more thankful for his long, curtain-like hair. He started listening at the bathroom door while Dean was inside doing it. He even caught him fucking some waitress up against a wall behind a bar, oblivious to his little brother in the shadows of the neighboring alleyway.

After the fourth interruption - Shower Incident #2 - Dean was starting to suspect that Sam was doing it on purpose. But that certainly wasn't going to make him stop, so Sam continued coming like a freight train to memories of Dean getting himself off. He _tried _thinking about girls. He even "borrowed" one of Dean's copies of Busty Asian Beauties. But nothing did it for him like the images of his brother coming all over himself.

Sam figured he needed help.

...

For his fifteenth birthday, Dean decided it was time for Sam's first beer.

"In hunter years, you're already twenty-one," he explained. But Sam was still too gawky and baby-faced for a fake ID to be any good, so Dean bought a twelve-pack and drove them out to a field where they could watch the stars and drink.

Sam wasn't crazy about the taste, but he forced himself to finish the first bottle, not wanting to disappoint his brother. Dean clapped him on the back and popped another top for him. Sam grimaced but found the second beer tasted better than the first. And the third tasted even better than the second.

"You may have a weird book brain, but I guess you're a Winchester after all," Dean joked as he opened a fourth bottle for his little brother. Sam was already leaning on Dean's shoulder, trying not to fall off the hood of the Impala. By the time the fourth beer was gone, he'd consumed enough courage to turn Dean towards him and plant an extremely sloppy kiss on his brother's mouth. The older boy grabbed Sam's shoulders and held him off at arm's length.

"What the hell, Sam?" The youngest Winchester blushed.

"Gimme 'nother one," he slurred, reaching for the open bottle in Dean's hand. Dean jerked it away, causing the inebriated boy to fall sideways onto his lap.

"No friggin' way! Not until you tell me what the hell that was about!"

"I _want _you!" Sam cried, several decibels above normal, staring mournfully up at his brother. "I want you," he said more quietly, almost in a whisper. "You're all I can think about when I…" he trailed off and looked towards his lap, where a bulge was beginning to form. Dean was frozen with dread. "Every time I've seen you jerk off, I've got it filed away in my 'weird book brain.' The way your hand moves, the way you tilt your head back, the way you breathe, the way your lips move, the way your cock-" Sam was cut off abruptly by his head thunking down onto the hood. Dean had leapt off the car and was pacing by the trunk. He couldn't tell which disturbed him more: his little brother's drunken confession, or the fact that he was noticeably turned on by Sam's dirty rambling. Dean ran a hand through his hair, trying to figure out what to say, when a soft snore saved him the trouble.

"Jesus Christ, Sammy." He heaved his sleeping not-so-little-anymore brother into the passenger seat. He hoped Dad would either be gone or passed out drunk himself when they got back. Dean slid behind the wheel, glanced over at Sam's still child-like features, and shook his head. "You are gonna be the death of me, kid."

...

It took six months, untold hours of tears and begging, and one really killer bag of weed before Dean finally gave in to Sam's persistent pleas for a hand job. The older boy felt horribly guilty afterwards, even while still stoned, but Sam was so overjoyed that he yanked Dean's pants down and oh holy mother of God where did he learn to do that with his tongue?

So yeah, it was a little weird, probably illegal, and definitely not normal, but when did the Winchesters ever do 'normal'? When Sam's lips were wrapped like a vise around Dean's cock, 'normal' could take a long walk off a short pier. When Dean had one hand down the front of Sam's pajama pants and the other over his mouth so that he wouldn't wake Dad, 'normal' could go fuck itself. With a cactus.

When Sam's sixteenth birthday was about a week away, Dean asked him if he wanted to do anything special. He'd figured his brother might like to go to a ballgame or a concert, or maybe a museum (the little nerd), but when Sam whispered what he _really _wanted, Dean almost did a spit-take over a library computer. The librarian glared at the two boys, one turning redder than his plaid shirt, the other looking like the cat that ate the canary.

When the day finally rolled around, John attempted to make it special. They had dinner as a family at a place slightly nicer that usual - real salt and pepper shakers instead of packets - and Sam received some memory for his clunky old laptop. When John asked Dean what he was getting his brother, he stammered a little and said something about cruising through downtown looking for girls. John looked relieved that his birthday duties were over. As the boys drove off in the Impala, their father merely told them not to be out _all _night and then hauled himself off to the nearest corner bar.

In reality, downtown was exactly where they did _not _want to go. Dean drove them far out of town and pulled the car off onto a darkened dirt road. His palms were sweating with nerves, but the birthday boy was positively vibrating with excitement. As soon as the parking brake was on, Sam popped his seatbelt and flipped into the backseat. Dean gulped as the other boy started stripping his clothes off.

"D'you think we'll both fit back there? You're getting kind of tall…" Dean's mouth went dry as more and more bare skin of his little brother's ever-lengthening limbs was revealed. Sam noticed the hesitant look on Dean's face.

"Come on, Dean, you promised!" The older boy nodded, removed his jacket, and climbed over the seat.

_Pull yourself together, dude. You're Dean fucking Winchester. You do not get nervous about sex, even if it is with- dear sweet Christ that is my baby brother naked in the backseat of the Impala and when did he get muscles and how did my jeans get unzipped and-_

Dean's mind went blank as Sam's talented tongue wrapped around the head of his cock. Suddenly, he remembered why he thought this was a good idea. As Sam licked and sucked, Dean watched the younger boy's free hand flick open a bottle of lotion, squeeze some out, and disappear between his legs. Sam moaned around the cock in his mouth, and Dean shuddered.

"Always did like doing your homework, Sammy," he managed. He felt a subtle vibration as the other boy chuckled. Soon, he had to haul Sam off of him, afraid things would be over too soon. "You still want to do this?" Sam nodded frantically. "Alright, turn over."

"Nuh-uh, this way," said Sam, laying down on the seat and bringing his legs up over his head. Dean's eyes widened in amazement as his little brother's knees came level with his ears, feet touching the roof of the car.

"Jesus Christ, Sammy. I did _not _know you could do that. Since when do you take gymnastics lessons?"

"Dean. Shut up and fuck me," Sam ground out. Dean shivered. He always did like the direct ones. Bracing his arms on either side of Sam's head, he lined himself up and slowly pushed into the tight warmth. Sam's eyes scrunched shut as he willed himself to relax, and Dean's eyes just about rolled out the back of his head. The heat and pressure were unlike anything he'd ever felt before. He probably should have felt weird about the fact that his little brother was turning out to be his best fuck ever, but at the moment, he couldn't feel anything but awesome. He managed to focus when he felt Sam's thighs rest against his shoulders. Dean looked down with concern.

"You okay?"

"Yeah," breathed Sam, still trying to relax, "yeah, I'm good. It's just… big." Dean gave him a cocky grin.

"That's what all the girls say." Sam pulled an impressive bitchface, then clenched his muscles. The sensation shocked Dean so much he saw stars. Or maybe the stars were from banging his head on the car ceiling. After a minute to compose himself to the point where it _didn't _feel like moving in the slightest would make him come, he glared down at Sam.

"That's it, bitch. You asked for it." Dean pulled back and rolled his hips forward, gently at first, not actually wanting to hurt his brother. Sam let out a long low moan and grabbed for the back of the driver's seat. Another thrust, a little harder this time, and the younger boy's voice skipped a couple of octaves. Dean found a blissful rhythm, alternating between long, slow thrusts and quick jerks of his hips. Soon both of them were moaning and gasping for air. The windows of the Impala were fogged up worse than in a trashy romance movie. As Dean's movements became more erratic, Sam grabbed for the handle above the door and held on for dear life.

When Dean finally felt like he couldn't hold out any longer, he reached for Sam's neglected cock and pumped it once, twice, the third time sending him spilling all over Dean's hand, shouting his brother's name. Dean thrust once more, the spasms of Sam's orgasm sending him over the edge as well. The older boy collapsed on his brother, not caring about the mess. They lay there, breathing heavily, until Sam started to get a cramp in the leg that was still stretched up over his head.

Dean pulled out slowly, apologized as Sam winced, and leaned against the opposite car door. He was still out of breath, but he couldn't resist a smartass comment.

"Happy sweet sixteen, Sammy."


End file.
